Method of alkylating aromatic compounds



Patented Dec. 11, 1945 ALKYLATING AROMATIC COMPOUNDS METHOD OF OFFICE George Felix Hennion, South Bend, Ind., and Norbert Francis Toussaint, Louisville, Ky., assignors to E. I. du Pont de Nemours & Company,

Wilmington,

Del.-, a corporation of Delaware No Drawing. Original application April 30, 1940,

S erial No. 332,476. Divided and this application May 19, 1943, Serial No. 487,658

6 Claims. (Cl. zoo-e71) This invention relates to a new method 'of alkylatingaromatic compounds and more particularly to a new method for condensing an aromatic-compound with an aliphatic alcohol containing 3 or more carbon atoms.

It is an object of this invention to develop a. new method of alkylation which gives sat-.

isfactory yields of alkylated products. A further object is to provide a novel method of alkylation which makes it unnecessary to use pressure equipment or excessive amounts of condensing agent; A still further object isto develop a superior process for condensing an aliphatic alcohol with an aromatic compound. Other objects will appear hereinafter.

These objects are accomplished by the following invention according to which an organic compound containing an aromatic nucleus is alkylated by reacting said organic compound with an aliphatic alcohol containing at least 3 carbon atoms in the presence of boron trifiuoride and an assistant acidic condensing agent selected from the roup consisting of sulfuri acid and benzenesulfonic acid. The alkyl-ation products thus obtained can be separated into their constituents by simple fractionation.

The following examples illustrate but do not limit the invention. All parts are given by weight except where it may be otherwise noted.

Example I .Amyl benzene Example II.Dodecg/l benzene 0.5 mol of n-dodecyl alcohol Was heated for hours with 2 mols of benzene in the presence of 1 mol of 94% sulphuric acid and 0.5 mol of boron trifilloride. A 46.4% yield of monododecylbenzone was thus obtained.

ExamplelIL-Butyl benzene A 63 yield of mon-butyl-benzene was obtained when 0.5 mol of n-butyl alcohol was heated for 4 hours with 2 mols of benzene in the presence of 0.5 mol of boron trifluori-de and 0.5 mol of benzene sulphonic acid.

Example IV.DodecyZ benzene 0.5 mol of n-dodecyl alcohol was heated for 10 hours with 2 mols of benzene in thepresencepf 0.5 mol of boron trifluoride and 0.5 mol of benzene sulphonic acid. A 44.6% benzene was thus obtained.

The benzene sulphonic acid used in the two yield of mono-dodecyl preceding examples may be generated in situ by passing boron trifluoride into a solution of 1 mol of benzene and 1 mol of 94% sulphuric acid. This gives complete sulphonation, and the product may be used without further purification as a catalyst in this alkylation reaction.

In accordance with the procedure which is exemplified by the preceding examples many alkyl substituted aromatic compounds can be made by alkylating an organic compound containing an aromatic nucleus with an aliphatic alcohol containing at least three carbon atoms in the presence of boron trifluorlde and an assistant acidic condensing agent selected from the group consisting of sulfuric acid and benzenesulfonic acid. Mixtures of monoisopropyl benzene and di-isopropyl benzene can be obtained by thus alkylating benzene with either normal propyl alcohol or isopropyl alcohol. para-di-secondary-butyl benzene may be prepared by butylating benzene with normal butyl alcohol. Alkylation of benzene with either iso-' butyl alcohol or tertiary butyl alcohol yields mono-tertiary-butyl benzene and di-tertiary-butyl benzene. Reaction of benzene with normal amyl alcohol in accordance with thi invention yields secondary-amyl benzene and di-amyl benzene. Benzene may be alkylatedwith a. mixture of aliphatic alcohols containing 6 and '7 carbon atoms obtainable in the methyl alcohol synthesis to yield mono-, di-, and tetra-alkylated benzenes. Mono-octyl benzene, di-octyl benzene, and trioctyl benzene may be prepared in accordance with the present invention by alkylating benzene with normal octyl alcohol. Alkylation of naphthalene with octyl alcohol yields a mixture of mono-octyl naphthalene and di-octyl naphthalene. A mixture of mono-octyl beta-methyl naphthalene and di-octyl beta-methyl naphthalene can be prepared by alkylating beta-methyl naphthalene with normal octyl alcohol. The reaction of 2- ethyl-hexanol with benzene yields a mixture of mono-2-ethyl-hexyl benzene and di-Z-ethyl-hexyl benzene. When decyl alcohol is used to alkylate benzene, a mixture of monodecyl benzene and didecyl benzene is obtained. Similarly, when normal decyl alcohol is used to alkylatemeta-xylene, a mixture of the decyl and didecyl xylenes is obtained. Decyl tetrahydronaphthalene may be made by the reaction of decyl alcohol with tetrahydronaphthalene. When benzene is alkylated Secondary-butyl benzene and with normal dodecyl alcohol, mono-dodecyl benzene is obtained along with some dl-dodecylbenzene. Reaction of normal dodecyl alcohol with naphthalene yields mono-dodccyl naphthalene and di-dodecyl naphthalene. Reaction of normal dodecyl alcohol with diphenyl oxide yields mono-- 'dodecyl diphenyl oxide.

In place of the alcohols which are mentioned above we may use hexyl alcohol, cyclohexanol, methyl cyclohexanol, nonyl alcohol, etc.

It is apparent that a wide variety'of aromatic compounds can be alkylated by the methods disclosed above. In accordance with this invention it is possible to alkylate still other aromatic compounds such as cymene, anth-racene, phenanthrene, fiuorene, methyl benzoate, dimethyl aniline, acetophenone, carbazole, thianthrene, phenol, cresol, naphthol, anisole, phenetole, brombenzene, etc.

This application is ication, Serial No.

appl

Resort may be had to such modifications and equivalents as fall within the spirit and scope of the appended claims.

We claim:

a division of our copending 1. A process for alkylatingan organic compound containing an aromatic nucleus which comprises reacting said compound withan aliphatic alcohol containing at least 3 carbon atoms in the presence of boron trifluoride and an assistant acidic condensing agent selected from the group consisting of sulfuric acid and benzenesulfonic acid.

332,476, filed April 30, 1940.'

2. A process for alkylating an organic compound containing an aromatic nucleus which comprises reacting said compound with an aliphatlcalcohol containing at least 3 carbon atoms in th presence of borontrifiuoride and sulfuric acid.

3. A process for alkylating an aromatic hydrocarbon of the benzene and naphthalene series which comprises reacting said hydrocarbon with an aliphatic alcohol containing at least 3 carbon atoms in the presence of boron .trifluoride and an assistant acidi condensing agent selected from the group consisting of sulfuric acid and benzenesulfonic acid.

4. A process for alkylating an aromatic hydrocarbon of the benzene and naphthalene series which comprises reacting said hydrocarbon with an aliphatic alcohol containing at least 3 carbon atoms in the presence of boron trifiuoride and sulfuri acid. v

5. A process for alkylating benzene which comprises reacting benzene with an aliphatic alcohol containing at least 3 carbon atoms in the presence of boron trifluoride and an assistant acidic condensing agent selected from the group consisting of sulfuric acid and benzenesulfonic acid.

6. A process for alkylating benzene which comprises reacting benzene with an aliphatic alcohol containing at least 3 carbon atoms in th presence of boron trifluoride and sulfuric acid.

GEORGE FELIX HENNION. NORBERT FRANCIS TOUSSAINT. 

